Over 4.5 million children undergo surgery in the U.S. each year and about half of them experience moderate- severe postsurgical pain. Pain may also persist beyond the immediate postsurgical period and transition into chronic pain for some children. However, little is known about the prevalence of persistent postsurgical pain in the pediatric surgery population or of the impact of pain on children's physical functioning, health-related quality of life (HRQOL) and health service utilization. Understanding of the biopsychosocial factors that may predict a child's risk for experiencing persistent postsurgical pain and reduced HRQOL would address gaps in knowledge to allow for the future development of preventive interventions. The objective of this application is to document longitudinal trajectories of pain and HRQOL in children following surgery, and to identify individual differences that place children at risk for both acute and chronic postsurgical pain and deteriorations in HRQOL. The long-term goal of this research is to develop effective strategies to prevent persistent postsurgical pain in children. The K23 candidate is an assistant professor in the Department of Anesthesiology and Pain Medicine at the University of Washington and a pediatric anesthesiologist and pain physician at Seattle Children's Hospital. Her K23 proposal will capitalize on the wealth of resources available at the University of Washington School of Medicine and Seattle Children's Research Institute. The candidate has demonstrated commitment to a patient-oriented research career and proposes a five-year training plan with the support of faculty mentors who have expertise in pediatric pain, health services outcomes research, pediatric research ethics, and biostatistics. Through the research training plan the candidate will obtain specialized instruction in state-of-the-art pain and functional outcomes assessment tools, intervention research methodology, preventive research and mentorship in research career development. The research plan involves two studies. Study 1 will prospectively monitor pain and HRQOL before and after surgery in a large hospital-based cohort of children undergoing minor and major surgical procedures over the first month post-hospital discharge. Study 2 will prospectively measure individual differences (clinical and biopsychosocial factors) associated with change in pain and function before and over 18 months following major surgery in a smaller, well-characterized sample using state-of-the art measurement tools including daily electronic diary monitoring and ambulatory actigraphy. Preliminary data demonstrate the feasibility of the multi-method assessment plan in the perioperative and postoperative periods and ensure success in carrying out the proposed studies. Data generated from this research will be used to identify children at-risk for chronic postsurgical pain and impaired quality of life, an will guide later research to develop and test medical and behavioral interventions for at-risk youth. Completion of the proposed research and training plan will provide the candidate with necessary data and essential skills to develop into a successful independent pediatric pain researcher.